Feeding mechanism for pilgering mills



Nov. 19, 1935.

J. GASSEN FEEDING MECHANISM FOR PILGERING MILLS Filed July 51, 1954 Patented Nov. 19, 1935 UNITED STATES PATENT oFricE FEEDING MECHANISM FOR PILGERING MILLS many Application July 31, 1934, Serial No. 737,727 In Great Britain August 3, 1933 4 Claims.

My invention relates to feeding mechanisms of pilgering mills.

In the rolling of tubes on pilgering mills, it is customary to rotate the mandrel which carries the tube blank through 90 after each revolution of the rolls. This is done in order to eliminate the seam on the tube blank which is caused by the roll gap at one pilgering stroke by the action of the rolls at their next stroke and thus obtain a tube which is smooth all around its circumference. Until now, the rotation of the mandrel has been derived from its reciprocating motion which it has to perform according to the well known principle of pilgering mills, for instance --by means which comprises a helically threaded spindle connected with the mandrel and anut supported in the slide carrying the mandrel, locking means being further associated with said nut for the purpose of allowing a rotation of the spindle only at its forward movement. It will be clear from the foregoing that the twist of the spindle varies in proportion to the feeding of the mandrel, so that feeds of different lengths will necessarily bring about also different angles of rotation, and the desired angle of 90 is thus only obtainable with one particular feed. This is a great drawback.

It is therefore an object of this invention to provide a feeding mechanism for pilgering mills in which the mandrel can always be rotated about a constant angle regardless of its feed. For this purpose, I provide separate driving means for effecting the rotation of the spindle which are automatically started at a certain position of the pilgering rolls and stopped after a rotation of the mandrel about the desired angle.

A further drawback of the known feeding mechanisms of pilgering mills was that a stop had to be provided for limiting their travel. This stop was subjected to continual wear and therefore did not ensure an invariable length of feed. Furthermore the stop had to be adjusted or exchanged when the diameter or the feed of the tube blank was varied which was, however, sometimes very diflicult in view of the high temperature in the neighborhood of the rolls where the stop was located.

It is, therefore, a further object of this invention to provide a feeding mechanism for pilgering mills in which the feed can be limited without the use of a stop.

An embodiment of my invention will now be described by way of example with reference to the accompanying drawing in which Figs. 1 and 2 are sections through a feeding mechanism for pilgering mills embodying the invention, Fig. 2 being a continuation of Fig. i. Fig. 3 is a transverse section on line III-III of Fig. l.

I are pilgering rolls adapted to operate on a tube blank 2 which is carried by a mandrel 3;. The latter is connected by a coupling box 28 to rod 4 of the feeding mechanism which terminates in a piston H which is under the constant load of compressed air or another suitable propelling agent. I

The drawing shows that moment of operation at which a part of tube blank 2 has been elongated to the finished tube 23. The pilger rolls I have pushed back thereby the tube blank 2 tgether with the feeding mechanism against the pressure of the compressed air on piston 2i. On further rotation of the rolls I they disengage the tube blank, because of the shape of their pass, so that the blank will be fed forward toward the rolls I by the constant load of compressed air on piston 29. During the first part of said forward travel, the feeding mechanism is rotated about 90 together with the mandrel and the tube blank 2, in order to eliminate the seam caused by the roll gap at the preceding stroke of the pilger rolls.

This rotation of the feeding mechanism will be preferably obtained by the means hereafter described:

Splined to the hub 22 of piston 2| is a square spindle 5 so that it can reciprocate, but not rotate relative to hub 22 and rod 4. On a cylindrical extension of spindle 5 is mounted a ratchet wheel 6 which is engaged by a pawl 8 mounted on a lever I (Fig. 3). The latter is rocked forwards and backwards through link 9 by crank I0, independently of the reciprocation of the feeding mechanism. During the forward movement, the pawl 8 takes the ratchet wheel 6 with it, but slides idly over it during the backward movement so that it remains then in its position together with spindle 5. Crank H1 is rigidly mounted on shaft II, riven by means of spur gears I2 and I3 by a motor I4 flanged to casing 21.

In order that motor I4 be started anew with every revolution of the pilger rolls I, I provide a control disc 24 on one roll shaft, here not shown, said disc having a cam 25 which operates a starter switch 26. I provide further a control disc I5 on shaft I I which disc operatesa second switch I6 for stopping motor I4, after spindle 5 and mandrel 3 have been rotated about the desired angle of 90. The speed of the motor will be so selected that even with the shortest feed available on the mill the rotation of the mandrel will not take too much time.

Control discs l5 and 24 are both adjustably mounted on their respective shafts so that the starting and stopping of the motor can be timed at will. It will be further clear from the foregoing that my invention is not limited to any specific angle of rotation, but that any desired angle can be controlled with it.

For moving the feeding mechanism described towards the rolls l, I provide a spindle l1 engaging a nut IS on the carrier IQ of the mechanism. Spindle I? is driven from a motor, here not shown, by means of spur gears 28, 29. This motor is started and stopped by control means similar to those described with reference to motor H.

A control disc 30 having a cam 31 is driven by pilger rolls l, forinstance by a chain or any other suitable means. Cam 3| operates a switch 32 for starting the motor. In the embodiment shown the control disc 30 is rotated relative to rolls I in the ratio 1:2 so that the carrier I9 will be fed to the rolls I only after each second revolution. It will be obvious, however, that by suitably selecting the transmission gear between rolls I and control disc 30, or by even mounting disc 30 directly on one of the shafts of rolls I, any des red feed control can be obtained. A second control disc 34 is provided which is driven from spindle I? for operating switch 33 which stops the motor. Control disc 34 may be driven from spindle ll by a transmission gear which is continuously variable so that any desired feed may be obtained.

I claim as my invention:

1. In feeding mechanism for pilgering mills, the combination with a mandrel for carrying a tube blank and means for imparting a linear motion to said mandrel, of means for rotating said mandrel about a predetermined angle independently of said linear motion, and separate means mandrel about a predetermined angle independently of said linear motion, and separate means for starting and stopping said rotation, said starting means being operatively associated with and adjustable relative to the rolls of the mill and said stopping means being operatively associated with and adjustable relative to a member of said rotating means.

3. In feeding mechanism for pilgering mills, the combination with a mandrel for carrying a tube blank and means for imparting a linear motion to said mandrel, of separate means for starting and stopping said linear motion, said starting means being operatively associated with the rolls of the mill and said stopping means being operatively associated with a member of said linear motion imparting means, means for rotating said mandrel about a predetermined angle and means for controlling said rotating means independently of said linear motion.

4. In feeding mechanism for pilgering mills, the combination with a mandrel for carrying a tube blank and means for imparting a forward motion to said mandrel, of an electric motor for rotating said mandrel about a predetermined angle independently of said forward motion, an

electric switch for starting said motor, an adjustable member rotating with the pilgering rolls and adapted to operate said switch, a second switch for stopping said motor, and an adjustable member rotating with said motor for opcrating said second switch.

J OSEF GASSEN. 

